So, What Is The Purpose Of The Blues, Anyway?

So what is the purpose of the blues, anyway?

No silly, not the blues itself. That's like asking what the purpose of haiku is, or sonnets, or romance stories or symphonies or kittens or... On that level, it's too big.

No, what's the purpose of the blues scale? Now that I might be able to understand, if only a little.

First, remember that the "blue notes" have been around far longer than myth and legend tell. Bach knew of the blues, harmonically; take away the written scores and music itself, so far as we know it, has the blues. Built in, as it were.

But, what about that old devil itself, the blues scale? Flat the third, flat the fifth, flat the seventh, but keep the major third and major fifth and lose the major seventh. So, counting both notes of the octave, that's nine notes, as opposed to eight.

Pretty much the first true jazz improv class you get handed this. And, when you, I, ask what to do with it, you get told "Use it to solo the changes."

The blues changes. Four bars of the I, two of the IV, two more of the I. Then one bar on V, one bar on IV, and we turn around with one of I and one of V before starting it all over again. Or, at the end maybe we turn that last V to resolve on the I. V-IV-I-V.

In G, the I is G, the IV is C, and the V is D.

They tell you, the G blues scale lets you solo or compose a melody over all of these chords, the I the IV and the V, using just the nine notes of the blues scale. How does that make sense?

Well, if we flat the seventh of G, that's F (and we ditch the F sharp entirely). F natural is just the fourth of C, but it's the minor third of D.

If we flat the third of G, that's B flat (but we can keep the B itself, too). B flat is now the flat seventh of C, and it's now the minor sixth of D.

And finally, flat the fifth (or raise the fourth) of G (keep both the fourth and the fifth), that's C sharp. C sharp is the flat 9 of C, and it's the major seventh of D. Odd that last, because the V is almost always the V7, i.e. the flat/dominant seventh if we're keeping diatonic, but hold that thought.

Good lord, what have we done? I mean, it makes sense, once you hear it. Please, at this point, these harmonies are so embedded in our ears that we don't even have to think about it.

But now we are thinking about it. Look again at the V-IV-I-V, the final four bars of the sequence.

One trick the blues scale tells us we can do? Just play D-minor (the relative form) over the whole sequence. So (in D minor for the moment), emphasize the root (D) in the first bar, the flat seventh (C) in the second, the fourth (G) in the third, then back to the D and we're home.

And in the middle? That F natural tells us we're moving, and where, doesn't it? Hold it between bars one and two, and we're moving from the flat third of the V to the fourth of the IV. Or the B flat, from the minor sixth of V to the flat seventh of IV, similarly.

F natural, too, hold that over from the IV to the I and we're moving from the fourth of IV to the seventh of I. Bring in now the B flat and carry that to the last bar V and we're moving from the flat third of I to the flat sixth of V.

Ok, so it's a map. We could play chord tones only. An awful lot of melodies do just that.

Why the chromatic notes, then? Movement. They're signals, really. Ways of getting the ear from here to there in an interesting way.

It also hints at one more step we can do. Look at that C sharp again. Flat fifth of the I, flat ninth of the IV, major seventh of the D.

Look at the changes again in explicitly jazz terms: unless explicitly stated otherwise, they're always V7-IV7-I7-V7 in a jazz chart. So, C natural in the V, B flat in the IV, F natural in the I, flat sevenths the whole way through.

The flat ninth of D is E flat. Which is the flat third of C, and the flat sixth of G. Huh.

D minor 9, G minor 9. Hmm. Include the A flat (i.e, the flat ninth of G, the I) and we get C minor 9. v9, iv9, i9 in other notation. Take the hint the blues gives us, and now we have three minor 9 scales we can use to move around with.

Ok, that's a lot. But just remember that the chord tones need to hang around; melodies are hard enough to hold in your head as it is.

This looks for all the world like what we're really saying, then, is that if you keep chord tones anchoring, you can pretty much move between them however you want. And that is, for sure, what we're saying if we're playing jazz.

But look again at the way, say, B.B. King uses his "blue" notes. Emotively. Powerfully. The melodies are chordally driven, melodic, rhythmic, but then harmonically the King hits you between the ears with a flat sixth (13th if he's playing or singing way up there). Not randomly, purposefully. He's moving somewhere, sure.

But there, in that moment, sonically you're hanging forever in the blue between, in that space where the heart is forever lost. So yeah.

Maybe we have come back to the purpose of the blues.